[" Why does the temperature of a substance remain constant during its melting point "],[" or boiling point? "]

Why does the temperature remain constant during the melting of ice even though heat is supplied continuously ?

Why does the temperature of a liquid become constant at its boiling point all thorough it is still being heated ?

For any substance, Why does the temperature remain constant during the change of state?

When water boils, why does its temperature remain constant?

For any substance, why does the temperature remain constant during the change of state?