They definitely don't feel pain the way we do. They can recognize deadly situations and react or escape to protect themselve, but it's not the same as reacting to a physical pain.
Maybe it's fear I dunno. Either way I don't look at boiling them as torture
I bet you're using Eurocentric science as your source...the source that doesn't even respect the humanity of individuals in their same species simply because their skin color is different.