All the (super) cool kids are doing it

One of the super-fun properties of water is that, under certain conditions, and without many impurities, you can cool it slightly beyond its freezing point (called "super cooling"), then perturb the system, and instantly freeze the water.

What you need for this experiment:

1. Filtered water (some tap water will work, but bottled waters generally work well).

2. Salt and ice water mixture (ice made from tap water is fine) in a 3/4 ratio of salt/ice water

3. Large bowl/container

Instructions:

1. Mix the salt and ice water so that it is dense with ice, and will support your bottles of water.

2. Open lids on filtered water (Opening lids after the bottles are super-cooled could lead to instant freezing. You can leave the lid on loosely, or just take it off.).

3. Sit bottles of water in the salt and ice water mixture for approximately 40 minutes. You may need to check on them slightly before. It is good to have a "tester" bottle of water that you can check to see if the water is super-cooled.

4. After water is super-cooled, pour onto a substrate (ice works well). This will perturb the system and lead to instant freezing of the super-cooled water.

You can find alternative instructions here. 

Observe:

Science is awesome.