system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: Why do sugar granules dissolve faster in liquids when you stir them with a spoon, than just leaving it to sit?
gpt
When something starts dissolving in water, it increases the amount of stuff dissolved in that particular part of water. The more stuff is already dissolved, the less likely it is that more dissolves into it.

If you just leave it sit, diffusion is the only process that carries the dissolved molecules away so fresh water without anything dissolved can come by to pick up more molecules. If you stir, you artificially accelerate the carrying-away of dissolved molecules, making more space for new ones to dissolve faster.