Liquid oxygen sticks between the poles of a strong magnet until it
boils away into its gas state. This is because it has unpaired electrons, which make each oxygen molecule a tiny magnet
with a dipole. Normally, when oxygen is in a flask or in the air, these
microscopic magnets point in all directions, cancelling out and meaning that
there’s no net magnetic field. When it pours over the permanent magnet, the magnetic
molecules all slightly align, creating an induced
magnetic field, which reacts with the permanent magnet, making the oxygen stick
to the poles. This is called paramagnetism. Click here to watch the video.