Wah How to use "So + Adjective / Adverb + That"

So means very,extremely
It's use when you want to describe why the result happens.
The result happens because It's so..

      So + Adjective + That
      You are so cute that I cannot take my eyes off you. 
      (You are very cute that is why I cannot  take my eyes off you.) 

      This movie was so funny that I could not stop laughing.
      (This movie was extremely funny that was why I could not stop laughing.)

      The weather here is so hot that I don't want to go outside.

      So + Adverb + That
      Don drive so quickly that no one wants to go with him again.
      Micheal snores so loudly that we don't want to sleep with him.
      Wah Wasabi's website explains English grammars so clearly (that) I can understand them easily.

In general, It's not necessary to use that.
You are so cute I cannot take my eyes off you. 

Jason Mraz sings in "I'm yours" song..
"Well, you dawned on me and you bet I felt it
I tried to be chill but you're so hot that I meltedI fell right through the cracksNow I'm trying to get back..."