  Searchers for various irregularities in the behavior of thermodynamic
quantities at chemical freeze-out (CFO) are rather important in a view of
experimental studies of quark-gluon plasma (QGP). Using the multicomponent
hadron resonance gas model (HRGM), developed in (Sagun, 2014; Bugaev et al.,
2015), we performed a high-quality fit of 111 hadronic ratios measured for 14
values of the center of mass collision energies between 2.7 GeV and 200 GeV
with the overall fit quality $\chi^2/dof \simeq 0.95$. In addition to
previously reported singularities (Bugaev et al., 2015) at CFO we found that
the hadron yield ratios $\frac{\Lambda}{p}$, $\frac{K^{+}}{p}$,
$\frac{K^{+}}{\Lambda}$, $\frac{\Omega^{-}}{p}$ and $\frac{\Xi^{-}}{p}$
measured in central nuclear collisions demonstrate a significant change of
slope in the same range of center of mass collision energy $\sqrt{s_{NN}} =
4.3-4.9$ GeV (Bugaev et al., 2015). This change of slopes is accompanied by a
dramatic increase of resonance decays at CFO.
  Also at CFO the trace anomaly and baryonic density demonstrate the pronounced
peaks at the collision energy $\sqrt{s_{NN}} = 4.9 $ GeV. We argue that all
these and previously found irregularities provide an evidence for the QGP
formation in nuclear collisions at about $\sqrt{s_{NN}} = 4.9 $ GeV.
