This video is beautifully animated, and brilliantly explained. It does mention a few bits you won't have heard of, and that we don't cover in AQA GCSE science.
It talks at one point about dipoles. This is talking about water - a water molecule (H2O) has lots of electrons around the oxygen atom (6 in it's outer shell, plus the two shared covalently with hydrogen) - the electrons are negatively charged, so the oxygen end of the molecule is slightly negatively charged (and there fore attracted to positively charged ions dissolved in water). The hydrogen end of the molecule is slightly positively charged (the electrons are all up by the oxygen) meaning there is a slight attraction to the negative ions dissolved in the water.
We can call water a polar molecule - it has two poles (like the poles on a magnet). This is what makes the bear joke funny! "Dipole" = two poles.
Source: BBC Bitesize
