Origin of supercoolability in metallic and halide melts is discussed. While the level of supercooling in metals is closely connected with the structural incompatibilities between the molten state and product crystal, respectively, the supercoolability of halide melts is caused by their strong complexforming nature. The investigation of processes in supercooled melts is important, because the supercooling of melt strongly influences the nucleation and growth of crystals from the melt and their final quality. Electrical resistance is a suitable quantity to study the solidification of melts, since it can be measured both in liquid state (including supercooled melt) and during the solidification. The early stage of solidification of PbBr2 melt was analyzed within the context of nonstationary nucleation theory. The proposed model describes the time dependence of electrical conductivity of the melt. The time lag of nucleation is calculated and compared with the experimental value.