How does a change in the temperature of the boiling point indicate that a chemical reaction has occurred?

A change in temperature is characteristic of a chemical change. ... If temperature increases, as it does in most reactions, a chemical change is likely to be occurring. This is different from the physical temperature change. During a physical temperature change, one substance, such as water is being heated.

If a reaction is a chemical reaction, then a change of temperature can be noticed, it can either be endothermic  (a decrease in temp.) or it can be exothermic (increase in temp.). Any kind of change in temperature of a substance is considered as a characteristic of a chemical reaction.

the dissolution of polymer can be thermodynamically described in 2 steps.