I hate people like this. With this attitude, everything we learn will never be passed on and die in a single generation.
Freezing Method:
very tedious
cool the 3% Hydrogen Peroxide solution just to the point where ice crystals start to form and filter them off, repeat until desired concentration
Boiling Method:
not viable due to a high degradation of H2O2 caused by the high temperatures
however, it can be done so long as you do NOT FULLY BOIL the solution and keep the solution free of dust, agitation, and anything that will increase the rate of degradation
there should very little if any bubbles coming off, the point here is to just increase the solutions rate of evaporation
Rotovap:
best yielding method, requires a rather expensive Rotary evaporator and is not suitable for amateur chemists.
BEST METHOD - Vacuum Distilation:
does require some glassware but the apparatus can be built for ~$50 on ebay
if you are an amateur chemist you most likely will just need to spend $10 on a cheap pump and power supply (will already have the distillation apparatus)
almost as good a yield as the rotovap
Pull the best vacuum you can with your equipment or right before the solution is about to boil
Apply a minimum amount of heat to the distillation flask containing 3% H2O2 (to prevent degradation)
The concentration of final H2O2 product can be estimated by the volume of water that distilled over
