スープが逃にげようとしているなら、まだ料理し終わってないってことだよ。 That's an actual line from a game we translated (The Whispered World). And the reason it uses なら instead of たら or ば tells you everything about how Japanese conditionals work. なら: the speaker SEES the soup escaping, assumes it's true, and draws a conclusion. Deductive reasoning. Change it to たら? Now you're saying "once the soup escapes, then. . . " Like you're waiting for it to happen. Change it to ば? Now it's a law of physics. Soup escapes = not done.