She made fire for the parents. By poofing air through a rubber tube, after pouring powder into a container (hidden in a larger, open-topped box), and lighting (something out of sight, so I don't know if it was a fuse, or the powder directly). The tube added air to the mixture and the flame was 8 feet high (from the floor - the table was probably 3' of that).
Or maybe, if Hagrid taught Potions. ;)