I was about an hour into a large print (PLA, 220C hot end, 70C bed, fan on) when I heard something hit the floor. I ran over to the printer and found my workpiece in the floor with the printer still functioning. I stopped the printer and raised up the Z axis and found a large 'beehive' shaped blob of plastic around the hot end. It looks like the plastic had been extruding onto the hot end for quite some time, and so much built up that it pushed the printed workpiece right off the hot bed.

The plastic is surrounding all four wires on the extruder and looks like a pain to remove it. Has anyone had this problem? I'm not sure what caused this in the first place. Help!

Is this a new printer or one that was previously working well? Just trying to understand how that could have happened.
If it's new and poorly calibrated it could be over-extruding plastic. If there is a leak in the hot end the plastic could be coming out of the side.
First clean it up then try another print, watching closely to see what happens - maybe shoot a video of it at the same time.

I would suggest heating the nozzle up half-way, say 80-100C, to soften the PLA and then carefully peel it off the wires, taking care not to damage any of them.

Nope, not new. I've been using it for over a month now and have had several successful prints of all sizes. This print in particular was one of the largest I've tried, but I've successfully have done bigger as well.

The part that got kicked off was horribly warped like a banana. Perhaps the ends curled upwards causing the nozzle to drag at the extremities of the part.