I was wondering this myself. I've been bulimic for 11 years now and I just recently started to get this horrible pain in just one spot on my head. I read something that said that bulimia cannot cause aneurysms but it may cause a preexsisting one to rupture during a purge episode. (Meaning you would have had to either been born with it or it formed because of a health issue other than bulimia).
I highly doubt this could possible occur during a vomiting episode. I've been bulimic for over 18 years. Sometimes I have strained myself so hard during vomiting that my nose starts bleeding. It hasn't happened often, but it scared the bejesus out of me! Believe me, if bulimia (vomiting) caused brain aneurysms, I'd have had dozens by now!