Creating raindrops that pop in and fade out?

I’m working on creating a rain material to work with different other materials, i.e. Windows, plastics and metals. Now I’ve achieved having the raindrops on another material but I have not yet been able to get the rain to pop in, then fade away. Much like this https://twitter.com/klemen_lozar/status/953731352175587328 Does anyone know how I can do this?

Thanks

A reference for the related effects: