Can I re-cork a beer bottle? If I open a bottle of Belgian beer-with a cork- drink a little then put the cork back in the bottle will the cork randomly pop or the bottle explode from any pressure?
Yes, you can do this just like a bottle of sparkling wine. It should keep the beer for a couple of days, but not forever. Sometimes the corks don't work great, so I would buy a Champagne bottle stopper like the one below 
Don't get the one that hold onto the ridge under the bottle opening. They work great for Champagne bottles but not so good on Belgian beer bottles.