We had a pretty crazy science teacher when I was in grade 8. If we'd been anywhere in the West he would have probably been suspended for gross negligence faster than anything, but we kids loved him :D
One day we were covering chlorine in chemistry class, so he simply decided to make some. We didn't have a fume cupboard or anything (our lab at the time was still very rudimentary), so we simply set the equipment up on a desk and waited for things to happen. When green smoke started billowing forth, we hurriedly opened all the windows and evacuated the lab. All other science lessons that day had to take place in different classrooms...
This was the same guy who showed us the thermite reaction - indoors - and with whom we used potassium+water to light a bunsen burner when we'd run out of matches. This year I was back at that school, now as a science teacher myself, and was there for the move into a fancy new lab building. But the old lab still had the burn marks on the ceiling, from some of his wilder experiments...
Indoor thermite and burn marks on the ceiling (and other stuff I won't mention now) also happens in the US, at least as of 10 years ago when I was in high school. I loved that class.
I managed to chlorine-gas myself right before a date once because I threw a little bleach on the bathroom floor before I took a shower and it turns out there was a mostly dried puddle of piss in the same spot. Only thing worse than chlorine gas is chlorine gas that's been nebulized from steam...
