Hmmm....
No puking, but I'm doing hack squats and keep the weight on the lighter side so I don't blow out my knees.
I do regularly get blurred vision while squatting and feel lightheaded when I rack the weights. I have naturally low blood pressure, so I think it's the spiking BP dropping that makes me lightheaded. When a serious BP drop happened when I sprained my ankle a few years back, I got seriously nausous. Perhaps that's what causes it.