Observations of stationary subcooled nucleate boiling with forced convection in a glass-pipe at a pressure of 0.1 MPa lead to a new interpretation of the superheated liquid state wetting the heated wall. This interpretation applied to the rules of linear non-equilibrium thermodynamics results in framework equations with non-linear heat transfer as indicated by several empirical correlations. Momentum balances at the singular surfaces of a bubble have been combined with a sonic limit for the mass transfer through the interfaces serving as a maximum condition with respect to heal transfer (DNB). The calculation predicts the corresponding wall temperature from properties of state without using empirical coefficients and therefore must be valid independent of coolants’ geometries and surface conditions. Documented measurements al pool boiling, forced and free convection with cryogenic liquids, water and liquid metals emphasize this if data are properly selected corresponding to the precondition that void fraction remains low.