system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: Why does food stick so strongly to plates or frying pans after its sat out a few hours compared to when it's fresh?

I was doing dishes today and had a couple particularly old stubborn smears I had to clean off. Even food items that were never hot (like guacamole or sour cream) seem to bond abnormally strong to dirty dishes after a night's rest in the sink. Why are they so stubborn!?
gpt
When food is wet, it tends to be soft and goopy.  In this liquidy state it can seep into microscopic cracks and such.  As it dries out, it loses moisture and both shrinks and hardens.  As it shrinks and hardens, it solidifies its grip on the surface as if it were clenching its fists.  Once it's hard, as all hard things are, it becomes difficult to move and thus to clean.