How does stirring affect the rate of solution formation?
The amount of solute that will dissolve is affected by temperature - more will dissolve at higher temperatures. This is called the solubility of the solute . Graphs of the solubility at different temperatures can be used to determine how much will dissolve, or at which temperature a given solution will become saturated.
Stirring simply moves the solvent molecules around, allowing them to interact with the solid pieces of undissolved solute and transporting the dissolved solute away into the bulk of the solution.
In the absence of stirring, the concentration of solute will be highest close to the pieces of solute, so more solute won't dissolve into the solution until the dissolved solute has been transported away by diffusion.