For the past month or so our 99' Pontiac Bonneville has been leaking antifreeze, not much, just a small amount. Yesterday we put more antifreeze in, and this morning, there wasn't any in there. We filled it up and it appeared to be running fine. When I picked my kids up from school I left the car running and when I came back, I could see a ton of antifreeze on the ground and the car was smoking under the hood. I drove it home (a few blocks) and lifted the hood. It was smoking terribly and I could see that antifreeze was on some of the parts (on the passengers side). I took off the oil cap and smoke began pouring out. I am just wondering if anybody could tell me what could be the problem?

The problem? You have an antifreeze leak and you are taking crazy chances with ruining the engine if you haven't done so already.

Best to go and get this looked at and fixed if it's not too late.

Don't drive the car, until the problem is fixed--have it towed. Otherwise, you could warp the aluminum head, damage the valves, and blow the head gasket. This can easily run $3,000. Hopefully, this hasn't already happened.

The problem, you did not fix it when the issue started. Cars don't just leak antifreeze.

A hose is broken or has a leak, or the water pump is leaking, This is putting antifreeze and water on a hot engine, what you see is steam not smoke.

If it runs too long, hot, it will ruin the engine and the car will basically be scrap metal.

When you got back, you should have shut it off and let it cool before ever trying to run it.
Was not the warning lights or gauges all showing hot ?

Never, ever drive a car that does not have water and antifreeze in it.
Within a few blocks, it can ruin the car.

So don't drive it one inch at this point, as noted, have it towed to a repair shop and fixed,