If you are a large brewery selling beer internationally and want to reduce the cost off shipping a product that is mostly water across the globe, there are several options.   You can build your own brewery abroad, closer to the market you are selling to but this involves a large investment.   You can have an existing brewery in the country closer to the market brew you beers under license, but this involves losing some control over the finished product.

Of course if you have a premium product and your customers are prepared to pay for this premium, then you can just ship it - for example Budweiser Budvar brews all its beer in České Budějovice, Czech Republicⁱ but is drunk all over the world.

Labbat's of Canadaⁱ came up with the idea of concentrating their beer, shipping it across to Europe and then rehydrating it on arrival.   They chilled the beer until ice crystals formed around nucleation sites - stray bits of yeast, protein and other impurities - then filtered the beer to remove the ice crystals and impurities.   This is a little like freeze distillation, where the ice formed first is pure water and removing it concentrates up the rest of the solution left behind.

The resulting rehydrated, finished product wasn't a success however.   Marketing came to the aid of this expensive dead end in brewing however and ice beer was born!   Only slightly higher in alcohol so that it doesn't really affect the taste, the beer can be marketed as "pure" due to the filtration process - which would happen anyway but without the formation of ice.   In a stagnant marco-brewed American style lager market where image & advertisingⁱ is the only difference between many beers, this was a shot in the arm.

Similar, but not the same as Eisbock - first invented by accident in Kulmbach, Germanyⁱ.