High school science story time:

When I was in school, we had a gym teacher fill in for the chemistry teacher. Not as like, a substitute teacher for a day or a week or whatever, but due to some kind of staffing or budget issue the gym teacher taught that whole semester. His science background would have been what he learned in high school himself thirty years earlier, but he was a warm body that could read a textbook so that was good enough for the administration.

Anyway, there was this demonstration they'd do where they'd drop a chunk of sodium in water, and as an alkali metal it reacts with heat, sparks, and maybe a small explosion. Now, you're only supposed to use a tiny amount for the demonstration, so the teacher pulls out their chunk of sodium and cuts off a pea-sized piece for the experiment and wows everyone with the demonstration.

Every year you get at least one student who asks what happens if you used a larger piece. The chemistry teacher would explain about how the reaction scales up, and that it's too dangerous to perform in the classroom. But the gym teacher says, "Gee, I don't know. But this is supposed to be a science class, so let's do a science" and uses the entire supply of sodium.

So I wasn't actually in that class when it happened. I was in a classroom directly above the chemistry lab when there's an explosion that I'm sure could have been heard throughout the building. Incidentally, someone had called in a bomb threat a month or two earlier, either as a prank or to get out of exams or whatever. You can probably imagine the chaos in the classroom. Someone pulled the fire alarm and everyone evacuated, but I don't think anyone was actually hurt.

Anyway, there's still a hole in the ceiling tile and they don't do that experiment anymore.