Some German car with an M on it (99 M3 Coupe)

[Jake]

It's a wild guess, but I'm going to guess that the two white window clips ($4 each) that hold the window to the regulator are not sliding smoothly on the track, they provide too much resistance to the motor past a certain point and that makes something pop.

Take the door panel off and grease the shit out of the track that those white clips ride in.