Everything can dissolve in water because water is considered a universal solvent. Liquid water is cooler than solid salt and sugar, allowing them to dissolve easily.
Salt's ions and sugar's polar bonds are both attracted to the polar water molecules.
Small solutes like salt and sugar can fit in the spaces between large water molecules.
What change would increase the amount of solid solute able to be dissolved in liquid water?

Decreasing rate of stirring
Decreasing surface area
Increasing pressure
Increasing temperature