Step-by-step explanation:
An equilibrium system is defined as a system where rate of forward and backward reactions are equal.
This means that when a solid substance is changing into liquid state then with equal rate of reaction and conditions is it able to convert back into the solid state.
Therefore, when a saturated solution of NaCl is formed the by heating it, solution can be converted back into crystals of NaCl. Hence, we ca say that the system will be in equilibrium state.