Unexpected Blue Colors

I took the photos below while photographing only ordinary drops of pure, clean water falling in front of a black featureless background. In the first photo we see some unexpected blue color.

In the next photo we also see some unexpected blue color.

In the next photo we also see some unexpected blue color.

In the next photo we also see some unexpected blue color.

In the next photo we also see some unexpected blue color.

In the next photo we also see some unexpected blue color.

In the next photo we also see some unexpected blue color.

In the next photo we also see some unexpected blue color.

In the next photo we also see some unexpected blue color.

In the next photo we also see some unexpected blue color.