(or boiling point), the temperature at which the transition to vapor begins for a solution of given composition in the liquid phase. The bubble point is generally lower than the condensation temperature, at which a vapor of the same composition begins condensing into the liquid phase. Azeotropic mixtures, for which the two temperatures are equal, are an exception.

The relation of the bubble and condensation points of solutions to the compositions of the solutions is determined by Raoult’s laws and Konovalov’s rules and can be graphically represented by a phase diagram. The elevation of the bubble point of a solution compared with the boiling point of the pure solvent is studied in ebulliometry.