Liquid Cooling simply uses a liquid as a "very efficient" means of moving heat away from components. The Heat still needs to be dissipated, you have a hot liquid instead of hot solids. Liquids are easier to transfer heat - or a "heat exchanger" as most facility managers would call it.
Now, you have a new set of problems. You have a warm liquid, that tends to do one of two things; become a bio-broth of bacteria, algae, fungus and clog up the system; or a highly toxic broth that may corrode the materials through which it flows. The warm liquid will flow across dissimilar metals, plastics, silicon based seals and likely come in contact with air.
If the heating, corrosion and eventual oxidation create a crack, the liquid is under pressure and will begin to leak, as it leaks you now have what is likely a highly conductive liquid spreading across your electronics.
There are liquids that are less likely to do this, such as florinerts - but they are expensive and toxic and generally not sold into the consumer market.