  Systems of Bose particles with both repulsive and attractive interactions are
studied using the Skyrme-like mean-field model. The phase diagram of such
systems exhibits two special lines in the chemical potential-temperature plane:
one line which represents the first-order liquid-gas phase transition with the
critical end point, and another line which represents the onset of
Bose-Einstein condensation. The calculations are made for strongly-interacting
matter composed of alpha particles. The phase diagram of this matter is
qualitatively similar to that observed for the atomic He4 liquid. The
sensitivity of the results to the model parameters is studied. For weak
interaction coupling the critical point is located at the Bose-condensation
line.
