The temperature dependence of the density in pure HgTe melt and liquid CdxHg1-xTe for x less than or equal to 20 mol% CdTe has been investigated by the gamma-ray attenuation method. The anomalous character of temperature density dependence for the investigated melts should be noted. Both the density and concentration gradient being stable in time have been found by the density measurements along the sample height. This gradient presence can be regarded as a new physical phenomenon in CMT melts (cadmium-mercury-tellurium). The concentration and density gradient formation is being related to the peculiarities of intermolecular interaction nature. The observed change of volume properties in the melts mentioned above has been analyzed on the basis of the associated solution theory. The calculation success in associated model approximation was achieved at the expense of Hg2Te3 associate introduction into the model of the chemical structure for these melts.