Demo: Hidden Heat
Take two identical pans, each with the same amount of water in them, only one is solid ice and the other is water at room temperature.
Place both pans on identical burners and turn them on hi until the one that had water comes to a rolling boil.
At this point remove both pans from the burners and measure their temperatures: Surprisingly, the one that had ice in it now has water, but still at the same freezing temperature as it was when it was ice, while the other pan went from room temperature to boiling.

Both pans received the same amount of heat, but only one increased it’s temperature. Explain.