Magic Fluids is a free google app for download mobile devices running on Android. Touching the screen allows you to swirl colorful smoke and water.
When you press the Menu Button (three-dot button on newer devices) animation pauses. From there you can clear the screen, go to the settings menu or save the screenshot to file on external storage (it goes to /Pictures/MagicFluids/ directory). Note that external storage (which usually means SD Card, but on some devices external storage is actually internal) must be available on your device.