Awwwwww ... I think I know the answer, so dare I risk it ?
boiling is the keyword. water at 100 C. The heat is going into converting the water into steam. it's called a phase transition, and the heat, 'cos it's "hidden" is called "Latent Heat".
Similar thing happens when water freezes or melts. No change of temp, but change of phase.
Do I survive ?