system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: Why does your body keep trying to vomit when your stomach is already empty?

I'm staying home today because I am ill, and I have noticed that after vomiting three or four times within ten minutes, the last few times hardly anything came out. 

What gives? Does your body just not know when to stop or does it want to make super certain that you have been cleansed fully?
gpt
Your sympathetic nervous system senses something is wrong (like a stomach flu or poisonous food). 
Then pushes the evacuate button. But it takes time to reset. This lag or delay causes you to vomit a bit more :)