This is a small science project I tried when I wondered what would happen if a water balloon froze. (this is my first instructable, so go easy when giving comments.)
Step 1: Fill the balloon with water.
Fill the balloon till it gets to be the size of at least a basketball. then put it into a freezer droor.
Step 2: Freezing the balloon
When you take the ice out of the freezer, the water in the center will usually leak out. this means you did it right. it also gives it a see through appearance.
(freeze for at least 5 or 6 hours.)
when you go to freeze the balloon, make sure NOT to underfreeze. if you do, your ball of ice may crack and gush all over your freezer.
Step 3: Remove from freezer
when you remove the ice ball from the freezer, imediately bring the ice ball over to the sink.
A crack will usually form somewhere on the ball of ice, and water will leak from the center. If it doesn't leak properly try using some hot water to make a hole.
remove from freezer, and enjoy.
The alcohol will be driven inwards by the freezing process, leaving behind its carrier liquid. If done correctly, an outside layer of ice will form and an alcoholic slush of around 35%-40% will be formed in the middle.... No need to try and put it in there artificially. You just have to be careful with timing :)
Picture this - A (strong) cosmopoolitan mix with vodka and cranberry, around 10% abv. Put into a ballon, frozen as above with a liquid centre...
Nice red icy shell, with around 35% alcohol in the middle !!! :)
Try it with any mixed drinks, wine or beer. As long as the starting abv (alcohol by volume) is less than around 25-30% the freezing and driving out of the alcohol will work.
It is commonly practiced in Scandanavian countries to leave a batch of home brew outside overnight in the cold months to freeze into a block with a nice hit of strong stuff in the middle.
Give it a try!!
You might also be interested in this Instructable. It explains how you can rapidly freeze anything with a higher melting point than pure alcohol. It's not as safe to work with as liquid nitrogen and won't freeze pure alcohol but avoids the need to buy a vacuum flask.