What would you observe when
$(a)$ a saturated solution of potassium chloride prepared at $60\,^{\circ}\text{C}$ is allowed to cool to room temperature.
$(b)$ an aqueous sugar solution is heated to dryness.
$(c)$ a mixture of iron filings and sulphur powder is heated strongly.

(N/A) As the solubility of potassium chloride decreases with a decrease in temperature,solid potassium chloride crystals will separate out from the solution.
$(b)$ Initially,the water will evaporate,leaving behind sugar. Upon further heating,the sugar will undergo thermal decomposition and get charred (turn black).
$(c)$ Iron and sulphur react chemically to form a new compound,iron$(II)$ sulphide $(FeS)$,which is a black solid.