A method, computer program, and cooking device for detecting boiling of liquids. The invention is implemented with a computer program executed by a processor or other computing device of a cooking unit such as an induction range. The computer program comprises a code segment for receiving an indication of successive temperatures of the vessel and for calculating a slope of a curve representing the successive temperatures versus time; a code segment for detecting boiling of the liquid based on the slope of the curve; and a code segment for providing an output which may be used to indicate the boiling. The computer program may also include a code segment for receiving variables relating to parameters and/or characteristics of the cooking vessel to refine the boiling detection.