The concentration dependences of unit cell parameter, the x- ray liens width, microhardness, electrical conductivity and the Seebeck coefficient for the Pb2-xGexTe alloys were obtained. Anomalies of physical properties were revealed in the range of x approximately equals 0.008-0.02. The obtained results prove existence of concentration phase transitions occurring in any solid solution and are associated with percolation effects in impurity subsystem of crystal when percolation threshold is reached.