Observation :
Sugar crystals separate out. Inference :
The sugar syrup solution prepared is a saturated solution.
Therefore,
Additional amount of sugar cannot be dissolved in it at room temperature.
In a saturated solution,
There exists dynamic equilibrium between the solute molecules in the solid state and in dissolved state.
Sugar(aq) ⇌ Sugar(s)
The rate of dissolution of sugar = The rate of crystallization of sugar.
However, when it is heated,
Additional amount of sugar can be dissolved in it.
But when such a thick sugar syrup is cooled again to room temperature, sugar crystals separate out.
