Corn syrup is a thick, sugary substance typically used in food. Mercury is a liquid metal which is extremely toxic. Watch what happens when these two liquids with opposite properties are mixed.
Corn syrup is one of the most viscous substances on the planet, yet it has a surprisingly low density. Mercury, on the other hand, is a dense liquid metal with low viscosity. When mercury is dropped slowly into a glass full of corn syrup, each of the mercury droplets fall pretty fast to the bottom. A lot of air bubbles become trapped in the syrup. The bubbles seem suspended but they are indeed gradually floating up.