  Various phase transitions could have taken place in the early Universe, and
may occur in the course of heavy-ion collisions and supernova explosions, in
proto-neutron stars, cold compact stars, and in the condensed matter at
terrestrial conditions. Most generally, the dynamics of the density and
temperature at first- and second-order phase transitions can be described with
the help of the equations of non-ideal hydrodynamics. In the given work some
novel solutions are found describing the evolution of quasiperiodic structures
that are formed in the course of the phase transitions. Although this
consideration is very general, particular examples of quark-hadron and nuclear
liquid-gas first-order phase transitions to the uniform k_0=0 state and pion
condensate second-order phase transition to non-uniform k_0\neq 0 state in
dense baryon matter are considered.
