In chapter 9 we have Aaron demonstrating that he learned well how to do sacrifices from the instructions given in the previous chapters, serving as a model priest for the members of the Aaronite priesthood who edited these books together.
In chapter 10 we have a strange incident involving "strange fire" offered before YHWH, offered by the Aaronic priests Nadab and Abihu , who are summarily and divinely burned to death for their offering. Evidently, this particular brand of incense was not a "sweet savour unto the LORD" as are the offerings of cooked meat. The rabbinical and clerical exegesis of this passage offers every possible spin on the story, from Nadab and Abihu perishing in righteousness having conscientiously done their duty, to them perishing justly as a result of divine retribution for their vanity or even idolatry.
Here is a useful place to start reading about them if you want to know more. The lesson appears to be that unless you perform your priestly duties precisely in accord with the levitical codes, you may be smitten by G-d Himself. Interestingly, Moses commands Aaron not to mourn the passing of his sons and commands Aaron's surviving sons not to mourn their brothers, "lest wrath come upon all the people." Evidently, God protests family funerals, just like the WBC.
Finally, in chapter 11 we have a collection of dietary laws delineating what is kosher and what is abominable. Interestingly, G-d considers coneys, hares, swine, and shellfish are all to be abominations unto His people. Why then did He create them to be so darned tasty? Only G-d knows.