[Svartalfiar]

I had gallons of beer syrup but there was a problem — all of the alcohol evaporates during the process.

What process did you use to do this? Boiling it will certainly remove the alcohol, as alcohol's boiling point is lower than water. (If you caught it and condensed it, that's what distilling is!) You could have tried freezing it, as alcohol freezes at a lower temp, freeze just below freezing then removing the ice will remove mostly water.

[Kevmo]

It was a freeze-drying process like what they do for instant coffee.

Some company in Europe solved this problem, but they can only generate mixed drinks like Pina Colladas. It doesn’t work for beer because consumers have very distinct palates when it comes to beer. Sweeter drinks are easier to disguise.