system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: What is that feeling/taste you have after water runs up your nose?

For example, this morning while I was washing my hair in the sink I felt some water running up my nose and shortly after I had that weird feeling/taste in my nose.
gpt
The linings of your nose, sinuses, trachea, bronchi, etc are basically epithelial cells, mixed in with some others.  These cell types on these organs prefer a slightly salty coating because [complicated evolutionary reasons here which aren't pertinent to your question and an explanation would be very long winded].

When fresh water hits them, it screws up their osmosis and they suck up water until they burst.  This causes the pain you feel...your cells dying because fresh instead of salty water hit them.

Conversely, if you need to clear out an object, insect, or what have you from deep within your nose, make a weak salt solution with luke warm water.  This will eliminate the pain you feel while trying to extract the object.  If you can't get such an object free on your FIRST try, go see an ENT. :)