electric kiss

Forgive me if this question is silly. Have you ever had a kiss that made your heart feel like it dropped (in a good way), and then your whole body gets really warm? Kind of like a 'ZING' throughout your body. 
I assume this is what they call "sparks"? 
Anyone have ideas why this happens between some people and not others? Even strangers or a hook up can have it, so I wouldn't say it's the history between the two people.