Transient boiling experiments have been performed using a large, preheated test specimen exposed to a water wall jet on its top surface. Temperatures measured at discrete locations on the surface have been used with a solution of the transient heat conduction equation to obtain the temperature field throughout the specimen, as well as the heat flux distribution at the surface. Together with visualization of related two-phase flow conditions, the results yield new insights concerning coexistence of nucleate, transition, and film boiling as well as single-phase convection, on a surface. Results are presented for jet velocities and subcoolings representative of conditions in high-temperature materials processing.