Sounds like blown headgasket or cracked head.

Let it cool completely, refill it with plain water(save anti-freeze, use plain water for test)....Leave cap off radiator and start engine. Look to see if water boils out once engine is running....if so, the head gasket is blown or the head is cracked....you might get a little overflow once the water pump starts turning, but it shouldn't contain lotsa bubbles or look like boiling water.

Make sure to drain water from radiator and engine after the test so's it don't freeze overnight.