A certain type of lamp contains colored liquids these liquids form globs that break off and rise to the top of the liquid the glob rises due to what?

It is called a "lava lamp" and the effect is caused by the heat of the bulb in the lamp causing one of the liquids to warm up and become less dense than the other (it is denser in the cold state). The less dense glob then rises up and breaks off and travels to the top of the lamp where it cools then sinks once again to the bottom of the lamp.