My car leaked out ALL anti-freeze at once.

I drive a 96 Accord.

I was at the store, turned my car on and made my way to another store about half a mile away. When I got there the car started making a strange clicking noise. I parked, turned the car off, and then I kept hearing the fan turning on and off all on its own. I popped open the hood and there was a little steam coming out and when I looked under the car the coolant was pouring out from underneath until there was none left.

I plan on jacking the car up and seeing where the leak may have been tomorrow morning, but I would like to know if anyone knows what could have triggered this because the coolant poured out instead of leaking and all of it was lost even when the car was already off it was like my car was puking. Any suggestions or ideas?