I don’t remember anymore exactly when, but once I had this dream where a snake was restlessly going around in circles, trying to catch a rat or something. 

In the end, it succeeded, but when biting the rat, the rat had actually already disappeared and it seemed like the snake was in fact biting its own tale, thereby forming a circle. 

In my mind this image became fixed and nothing moved anymore. My concentration also became one pointed. After a short while I then woke up.

I was told later that this image of a snake biting its own tale is a sign of the rising kulakundalinii.