Braze-spatter is occasionally seen in furnace brazing and usually occurs when someone is using brazing paste. I have not personally seen it happen when solid forms of brazing filler metal (BFM) such as wire, sheet or solid rings are used. When braze-spattering does happen, it might look something like the weld-spatter shown in Fig. 1, or perhaps like the soldering spatter shown in Fig. 2.
People are often surprised when they see braze-spatter on parts coming out of their brazing furnace and wonder if the spatter was due to careless application of the paste, or perhaps due to sloppy parts-handling by personnel in the brazing shop, etc., and fail to grasp that the vast majority of braze-spattering has to do with furnace heating rates in combination with the size of the brazing-paste bead that is applied to the joint area.