One of the very interesting aspects in the high energy heavy-ion collisions experiments and in nuclear astrophysics is a detailed study of the thermodynamic properties of strongly interacting nuclear matter far away from the nuclear ground state. The main goal of this contribution is to show that thermodynamic instabilities and phase transitions can take place at finite net baryon density and temperature, where the onset conditions of deconfined quark-gluon plasma should not still realized. Similarly to the low density nuclear liquid-gas phase transition, we show that a finite density phase transition is characterized by pure hadronic matter with both mechanical instability (fluctuations on the baryon density) that by chemical-diffusive instability (fluctuations on the strangeness concentration). The main goal is to investigate how the constraints on the global conservation of the baryon number, electric charge fraction, and strangeness neutrality, in the presence of Delta-isobar degrees of freedom, hyperons, and strange mesons, influence the behavior of the equation of state in a regime of finite values of baryon density and temperature. It turns out that in this situation hadronic phases with different values of strangeness content may coexist, altering significantly meson-antimeson ratios.