  A novel attempt has been made to probe the QCD phase boundary by using the
experimental data for transverse momenta of {\phi} mesons produced in nuclear
collisions at AGS, SPS and RHIC energies. The data are confronted with simple
thermodynamic expectations and lattice QCD results. The experimental data
indicate a first-order phase transition, with a mixed phase stretching the
energy density between \sim1 and 3.2 GeV/fm3 corresponding to SPS energies.
