Laser-flash photography was used to document the onset of cavitation bubbles induced in liquid media by Q-switched laser pulses. Such bubbles are hypothesized to indicate the "breakage of water" by negative stress caused by the inverting reflectance of a laser-induced propagating stress wave at the air/liquid interface. Absorption of the pulsed laser by the liquid caused thermoelastic expansion which generated the initial stress distribution. These liquid phantom experiments model the situation for tissues where such "breakage" of the tissue structure can contribute to the process of tissue removal by the phenomenon called "spallation". The threshold dosimetry for cavitation and explosive vaporization were determined. The threshold negative stress for onset of water cavitation under the dynamic stress conditions induced by ∼ 140-ns laser pulses is approximately -8 bars.