  Thermodynamics properties of an interacting system of bosons are considered
at finite temperatures and zero chemical potential within the Skyrme-like
mean-field model. An interplay between attractive and repulsive interactions is
investigated. As a particular example an equilibrium system of pions is
discussed. Several modifications of thermodynamic properties in the considered
system are found with increasing a strength of attractive forces. Different
types of the first order phase transition are classified. Some of these
transitions exist also in the Boltzmann approximation. However, effects of the
Bose statistics introduce the notable additional changes in the thermodynamic
quantities due to a possibility of the Bose-Einstein condensation.
