What do we call it when a material is heated and changes into a liquid?

A materials vocabulary is the words used to describe matter. 'Matter' is everything that exists in the world. When we talk about a particular type of matter, we refer to it as a 'material' or a 'substance'. In order to talk about matter, its many different forms and their properties, we need to use the right vocabulary. Words like 'porous' or 'smooth' describe some properties and words like 'liquid' or 'metal' describe some types of materials. There are many different words used to describe materials.