When breaking a block, there is a chance to break the block neearby(the block is of the same type as you are breaking)

I started a new project on my creative world, when I was breaking bedrock and pistons, I noticed: the block nearby may break even if I don't destroy it.
I know I can't really explain myself better, so here is a GIF: https://gfycat.com/TenseBlushingAsianwaterbuffalo

P.S.: Sorry for uploading it on gfycat... The max file size is 10 MB here...