What is monologue? what is the difference between monologue and thinking to yourself and give the examples of monologue.

a long speech by one actor in a play or movie, or as part of a theatrical or broadcast program.
synonyms:soliloquy, speech, address, lecture, sermon, homily; formaloration

examples
"he quickly launches into another manic monologue"
a long and typically tedious speech by one person during a conversation.
"Fred carried on with his monologue as if I hadn't spoken"

You're speaking a monolouge, when you are thinking to yourself, normally not saying it unless to let an audience know. A monolouge can include what you are thinking or giving a speech.

Generally spontaneous human combustion is something that still bewilders some, human combustion happens very rarely and doesn't affect the surrounding areas, so unless you want to set your self on fire, human combustion will remain spontaneous and very rare.