So let's suppose we have a beaker of pure water. So inside the beaker, all we have are these water molecules that are moving about and which are interacting with other water molecules via hydrogen bonds. Now, let's suppose we take two non polar molecules and place them into our beaker. What will happen initially? Well, as soon as we place them into our beaker all these water molecules that were eventually moving around randomly and rapidly some of these water molecules will surround our non polar molecules and when they surround the non polar molecules they essentially are trapped. They become trapped to the non polar molecule and these water molecules can no longer move about as frequently and randomly as before.