The class was designed to encourage open conversation among immigrant students, but one new arrival from Egypt refused to remove the veil covering her mouth.
Faced with an ultimatum from her school and the Quebec government that she expose her face, the mother of three decided to quit the French class instead.
The woman has launched a human-rights complaint against the province - the first involving a woman's right to wear the niqab in Quebec - and set off more debate over the lengths to which public institutions should go to accommodate Muslims.
The head of the CEGEP de Saint-Laurent says the college tolerated the woman's demands at first, allowing her to wear the all-covering garment, with slits for the eyes, when class began in August.
She gave presentations from the rear of the classroom with her back to the class, which counted three men among 20 students. Hostility grew one day when she asked male students to move away from her. For one-on-one exercises, the woman would retreat to a corner with her female instructor, according to Paul-Émile Bourque, the head of the college in a Montreal immigrant neighbourhood.
But when a new segment of the class began in October, there was no guarantee the teacher would be a woman. The coincidental gender imbalance of the first segment would end just as the entire class was supposed to sit around a U-shaped table and converse. And teaching proper pronunciation is impossible when you can't see the student's mouth, Mr. Bourque said.
The school and Quebec's Immigration Ministry, which financed the class, decided the veil would no longer be tolerated. In a province where accommodating immigrants has become a toxic issue, Immigration Minister Yolande James approved the ultimatum.
"We tried certain arrangements, but the demands just became too great," said Mr. Bourque, who has faced criticism for making any special arrangements for the woman.
While one Muslim group expressed regret Monday that a compromise was not reached, some of Quebec's staunchest human-rights defenders say the woman expected too much from a public institution.
"There are limits to everything," said constitutional lawyer Julius Grey, who has defended the right of inmates to smoke in prison and the right of Sikh students to wear the kirpan, a ceremonial dagger, to school. "A person should be able to wear what they want, but I make an exception for the full veil in public institutions.
"Accommodation should not lead to separation. You hide someone, you allow them to refuse to speak to men in a public institution, they don't integrate. Besides, how do you learn a language if the teacher doesn't see your lips?"
The woman, whose identity remains a mystery, has not spoken publicly, but many commentators rushed to suggest she was a provocateur enlisted by Islamist extremists.
Mr. Bourque said he believes she was simply from a conservative area of Egypt and wasn't ready to change. The provincial Immigration Ministry defended the decision, saying everything was done to "reasonably accommodate" the student.
While the main goal of the course is to teach French, it is also designed to integrate immigrants gradually into Quebec society. "We could not accept [that]the objectives be compromised and neither could we accept to jeopardize the learning environment in the classroom," said Luc Fortin, a spokesman for Ms. James.
Mr. Bourque said his college program has helped a handful of women stop wearing veils over the past 10 years. The college has taught 8,500 students with no similar expulsions, he said.
With a report from Rhéal Séguin in Quebec City