We consider the thermodynamical properties of an interacting boson system at ?finite temperatures and zero chemical potential within the framework of the Skyrme-like mean-fi?eld model. Self-consistency relations between the mean fi?eld and thermodynamic functions are derived. For illustration of our approach the thermodynamic properties of a $\pi$-meson system are investigated. We numerically solved the self-consistent equation for a particle density and derived all thermodynamical functions as functions of the temperature for different values of an attractive constant of coupling $\kappa$. It is shown that for some values of $\kappa$ this system develops a ?first-order phase transition via formation of the Bose condensate at non-zero temperatures. Phase diagrams and the pressure $p/T^4$, energy density $\epsilon/T^4$, entropy density $s/T^3$, trace anomaly $(\epsilon-3p)/T^4$, speci?fic heat $C_V/T^3$, and the speed of sound $c_s^2$ are calculated in the liquid-gas and condensed phases.