You can purchase a gun from individuals (without a FFL) in most state's without a background check, at a gun show or anywhere. The background checks only apply when purchasing from FFLs in most cases.
Hawaii is a unique case where background checks are required for all firearm transactions from anyone.
Hawaii is not unique in that respect.
From "Giffords Law Center", and they should know...
Nine states (California, Colorado, Connecticut, Delaware, Nevada, New York, Oregon, Rhode Island, Washington) and DC require universal background checks at the point of sale for all sales and transfers of all classes of firearms, whether they are purchased from a licensed dealer or an unlicensed seller.38 (Note, however, that Nevada’s background check law, enacted through a voter ballot initiative in 2016, has not yet been implemented).39
Two more states, Maryland and Pennsylvania, require point of sale background checks for handguns but not for long guns, like rifles and shotguns.
Instead of a point of sale background check, four states (Hawaii, Illinois, Massachusetts, and New Jersey) require all firearm purchasers to obtain a permit, issued after a background check, in order to buy any firearm. Four more states (Iowa, Michigan, Nebraska, and North Carolina) have this permit and background check requirement for the purchase of handguns, but not long guns. Illinois also requires a point of sale background check whenever a firearm is sold at a gun show.