I know the term "eutectic" from brazing, where the chemical composition of your filler rod changes over heat/cool cycles. It comes up every once in a while, and I always reference something about cheese, and how it changes when it melts & cools (i.e. is non-eutectic).
So, I *think* I'm right for most cheeses. But as this points out, mozzarella (and low-moisture mozzarella in particular) seems to buck that guideline.
Anyway. The more you know.