It is generally known for $\mathrm{U}(N)$ gauge theory at finite temperature that phase transitions are manifested by taking the large-$N$ limit. Since the large-$N$ theory undergoes two thermodynamic phase transitions, a nontrivial intermediate phase can be realized in addition to the phases classified as the conventional confined and deconfined phases. In this talk, we discuss that a similar picture can be applied to QCD with $N=3$. In particular, we analyze the gauge configurations of lattice QCD calculations involving dynamical quarks and show the results of an analysis of the deviation due to finite-temperature effects from the Haar randomness expected at zero temperature in $\mathrm{SU}(N)$ gauge theory, using physical pictures suggested by the large-$N$ theory.