An endothermic phase change would be vaporization. I say this because endothermic changes absorb heat or energy. When something vaporizes it is because it was boiled or evaporated, which contains absorbing heat.
An exothermic phase change would be freezing. Exothermic changes release heat or energy from its surroundings and when something is frozen, it does not contain heat, it releases its heat.
Hope this helps :)
