  During the collapse of massive stars, and the supernova type-II explosions,
stellar matter reaches densities and temperatures which are similar to the ones
obtained in intermediate-energy nucleus-nucleus collisions. The nuclear
multifragmentation reactions can be used for determination of properties of
nuclear matter at subnuclear densities, in the region of the nuclear liquid-gas
phase transition. It is demonstrated that the modified properties of hot nuclei
(in particular, their symmetry energy) extracted from the multifragmentation
data can essentially influence nuclear composition of stellar matter. The
effects on weak processes, and on the nucleosynthesis are also discussed.
