My clutch popped
 

So, I have an 82 4x4 that I bought last year. I havent had time to do some work to it that i wanted to before using it as a daily driver so it's been sitting but i fire it up once a month or so, let it idle, put it in gear, etc. This time when i put it in gear the clutch was hard to press in and when i gave it a little more it popped and now has only tension from the spring up under the dash, no more pressure. The question is what did I do? Is there a cable that snapped or something hydraulic? I looked around underneath a bit and didn't see anything that struck me as wildly out of place but was so bummed I didn't spend a lot of time under there. Where should i start looking for the problem and if there's only one thing it could be, how tough a repair is it? I'm mechanically smart and mildly experienced. No real shop space to speak of. Also it has been outside in a fairly humid environment (I know, chastise me later)... Thanks in advance guys.

The first check for leaks. I would check the clutch fluid in the reservoir, if no fluid, the clutch slave cylinder will not actuate the the pressure plate. If there are leaks, then address where it's coming from. You said it popped, it could be the clutch actuator arm broke that holds the throw out bearing in place. Pull the seal off the side of the bell housing and take look. The clips that hold the throw out bearing in place may have broken. There have been occurrences of the of the clutch pedal bracket cracking and not allowing the pushrod to actuate correctly or the pushrod may have broken.. Maybe time to replace the clutch master cylinder. Just a few things that come to mind.

Everything Lons said.
You mentioned it's in a humid environment. One of your hard lines may have finally rusted through enough that you blew all the fluid out of a hole.
Replacing the master or slave and the lines between them is really easy and can be done in an apartment parking lot.