I once remember sitting in a Physics class, they shared with Chemistry and as we're sitting there one of the chemistry teachers started clearing up - not sure what happened exactly but all of a sudden there's a bang, red smoke and everyone starts coughing - we had to evacuate the entire section.
Turns out the teacher had poured some bromine down a sink, along with something it reacted with.
My strongest memory of high school chemistry is inhaling bromine vapors (I'm sure we were doing various addition reaction common in organic chemistry). It's got a very specific smell, rarely if ever encountered in the regular world.
The same chemistry lab had a sign warning us not to "pipette by mouth", but I actually do that today to transfer tardigrades. It gives you remarkable control over the volume transferred.
That is a strong indictment of US teacher training. (One assumes that's the US, because teachers are remarkbly untrained over there.) Everyone knows you deactivate bromine and chlorine with thiosulfate or sulfite and only then chuck it down the drain.
This could also be the common error where someoone tries to pipet bromine like it was an ordinary liquid:
Open the bottle (under the hood), there's not that much red smoke coming out, dip the pipet into the dark liquid, pull in a few mLs, looks normal, almost like you could precisely dispense small amounts into the nearby target apparatus.
Lift the pipet slowly out of the source bottle, and carefully position it over the waiting reciever flask. Don't be too concerned about exact amounts to be dispensed any more, it can be seen that precision with bromine is not as ideal compared to something like pipetting alcohol, where you commonly lose a few drops anyway.
After all, immediately when you withdrew the pipet from the bromine bottle, the entire contents of the pipet had spewed out from its own gas pressure, into the inside of the hood. Don't worry about the state of your reaction, not a drop of bromine landed where you had intended.
All you can do if you have your wits about you is to hold your breath, carefully put the stopper back on the bromine bottle (without knocking the whole thing over) and fully evacuate, basically following out behind everyone else in other parts of the lab who knew there was a problem as soon as you did, just from the smell.
Let's be clear: all over the world people handle bromine safely by taking the proper precautions. The boiling point is low enough to squirt the material out of the pipette you picked it up with. Consequently, you exercise some patience and delicacy, wear gloves that are thick enough and operate in a fume hood.
If you can't do that you should be doing something else with your life. This isn't computing where nothing worse is at stake than money, usually.
Turns out the teacher had poured some bromine down a sink, along with something it reacted with.