You reach a higher frequency of vibration,a higher state of consciousness. When the kundalini pierces the sixth chakra you see a flash of light and when it pierces the crown chakra and protrudes out some feet (like the pharoah diagrams)
it seems you'll achieve a higher state of consciousness. That's what Mageson says. Its called Samadhi.
Some people have a Samadhi type experience when the mundane mind disappears and the mind expands drastically and picks up on a higher wave of existence that has always been there