In our study we investigated the ablation characteristics of an aqueous dye solution with a defined absorption coefficient, irradiated by short (8 ns) and long (100 microsecond(s) ) pulses from a Nd:YAG laser (wavelength: 1064 nm). The experimental technique was schlieren photography with a second Nd:YAG laser at 532 nm as a light source and with a variable delay between the two laser pulses. With a special arrangement of the laser beams and the sample effects below and above the surface of the liquid could be simultaneously observed. We could distinguish three ablation mechanisms, depending on the pulse duration and the incident fluence. With short pulses and a fluence below the vaporization threshold the tensile pulse from the bipolar thermoelastic wave, propagating from the liquid-air interface into the sample, caused rupture and spallation of the liquid. At fluences generating a surface temperature in excess of 100 degree(s)C the short pulses caused explosive vaporization, characterized by shock wave emission both in air and in liquid. At the same fluence the long pulses caused slow vaporization, meaning that vapor and liquid ejection started during the laser pulse and was less violent than with the 8 ns pulses.