system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: why is it that when I'm boiling pasta with a lid on the pot there is foam trying to escape, but it goes down as soon as I take the lid out?

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gpt
When cooking pasta the boiling water will start to bubble because of the steam that is created in boiling the water, the starch that is released into the water by the pasta causes the foamy look. When you take off the lid, the steam that caused the bubbles can escape so the bubbles lower.