Constant temperature and pressure molecular-dynamics simulations in conjunction with constant pressure and enthalpy simulations, designed to examine the threshold behavior in laser ablation, demonstrate that the rate of homogeneous nucleation (explosive boiling) increases sharply in a very narrow temperature range at approximately 90% of the critical temperature. Moreover, the homogeneous nucleation is sufficiently rapid to prevent the superheated liquid from entering the spinodal region at densities greater than the critical density.