For studying certain boiling phenomena of superheated liquids, new methods for deactivating nucleation sites were developed They were based either on the local cooling of the test liquid in contact with the solid surfaces to subcooled or nearly saturated conditions or on replacement or covering of the vapor cavities by a buffer or test liquid. The procedures of vacuuming and subsequently pressurizing or locally cooling allowed investigation of a phase-change process, which possibly prevails during the accidental, instantaneous release of superheated liquid.