<p>Stimulated Brillouin scattering and optical breakdown induced by a single pulse in a 30-mm-thick layer of water with emission of the 656.27-nm H_α spectral line have been detected for the first time when a beam of a Nd³⁺:YAG laser (532 nm, 10 ns, 0.4 mJ) was normally incident and focused on the surface with a power several times lower than the critical self-focusing power 1.7 MW in water. At a laser pulse energy of 0.6 mJ, the optical breakdown occurs before the onset of stimulated Brillouin scattering thus blocking it. Experiments with an additional number of samples (acetone, ethanol, toluene, and CCl₄) have revealed the optical breakdown with localization near the surface, which is confirmed by the ejection of a droplet by a shock wave, as well as the generation of a hydrogen line in all samples, except CCl₄, where hydrogen is absent. The synergistic mechanism of nonlinear optical compression of the pulse and beam collapse with the achievement of the water breakdown threshold has been discussed.</p>