Could planets explode in space? Could a planet like the Earth or any other explode or be destroyed and did we see a planet explosion with Hubble?
We never saw a planet explosion with Hubble.

To make something explode it has to produce a lot of energy in a very short time. Gravitational collapse and thermonuclear fusion in degenerate matter are two possible ways of producing enough energy to produce a supernova.

These mechanisms can not cause a planet to explode. Planets are solid and supported by their own matter, so can't collapse, and they don't contain large amounts of hot degenerate matter, so don't have any kind of fusion.

Planets don't produce much of their own energy, and there is no mechanism known that could cause a planet to explode. 

The closest you may get is planetary collisions, such as that which likely formed the moon. But these have never been directly observed.