Superglue contains a chemical called cyanoacrylate which reacts with water in the air to harden. When manufactured, there is no water in the tube and so the super glue doesn't harden. As soon as the glue is exposed to the air, however, it reacts with any moisture and hardens.
If you want super glue to harden quicker you should breathe on it, as the moisture in your breath promotes the hardening process. And it's also why super glue sticks to your hands so well, as there's a plentiful supply of water on your skin.