Basically, the suggestion here is to implement raw tokens for materials that define the amount of energy that needs to go into it before it changes phases.
[HEAT_OF_FUSION:X]
[HEAT_OF_EVAPORATION:X]
[HEAT_OF_SUBLIMATION:X]
Where X is a unit of energy in the form of [SPEC_HEAT:of object]*volume of object.
When a material's temperature hits the threshold where it melts/solidifies, boils/precipitates, or sublimates/condensates, it will need to have a certain amount of energy added or removed from it to gradually change it's phase until it overcomes the HEAT_OF_X, changing fully into the new state.
Materials subject to contact with materials at temperatures dramatically above it's boiling point (specifically water, which has both high heat of evaporation and SPEC_HEAT) will draw in heat rapidly, allowing water to smother fire effectively in large quantities. Blood and fat cooking off as well will prevent a minor ignition from consistently burning through the whole body unless the victim is subject to extreme flames or made especially flammable by what covers them. Being covered in water at all will retard flammability somewhat, due to the HEAT_OF_EVAPORATION making it difficult to keep temperatures extremely high without causing the water to dry out first.
[VAPOR_PRESSURE:multiplier?] could be set for materials for the temperature threshold in which vapor pressure becomes a source of evaporation with the liquid, before it's fully gaseous. This can cause liquids in unsealed containers, for example, to gradually diminish due to "drying out" from vapor pressure evaporation, cooling somewhat continuously as a result.
Sweat, also, will actually cool the body, due to the vapor pressure. Being windy and covered in water in the middle of a tundra could cause some severe chilling if you don't have the proper clothes to protect against the water and wind.